In my earlier U.S. Pat. No. 4,451,094, which is included in this specification by this reference, I have disclosed a highly efficient hydraulic brake system in which the kinetic energy of the vehicle is adjustably used to pressurize an hydraulic fluid. The caloric energy which accumulates into the fluid upon its pressurization is dissipated through a cooling radiator as the fluid is allowed to escape its pressurized chamber. The present invention results from efforts to improve the aforesaid brake system by accelerating the dissipation of the fluid heat and enhancing the sturdiness of the mechanical system whereby higher fluid pressures can be accommodated while leakage can be minimized and controlled.